<template>
    <div>
        <h1>当前求和为：{{sum}}</h1>
        <select v-model="n">
            <option :value="1">1</option>
            <option :value="2">2</option>
            <option :value="3">3</option>
        </select>
        <button @click="increment">+</button>
        <button @click="decrement">-</button>
        <button @click="incrementOdd">当前求和为奇数再加</button>
        <button @click="incrementWait">等一会再加</button>
    </div>
</template>

<script>
    export default {
        name:'Count',
        data() {
            return {
                n:1,//用户选择的数据
                sum:0//当前和
            }
        },
        methods:{
            increment(){
                this.sum+=this.n;
            },
            decrement(){
                this.sum-=this.n;
            },
            incrementOdd(){
                if (this.sum%2) {
                    this.sum+=this.n;
                }
            },
            incrementWait(){
                setTimeout(() => {
                    this.sum+=this.n;
                }, 500);
            }
        }
    }
</script>

<style>
    button{
        margin-left: 5px;
    }
</style>